Cell cycle arrest and autoschizis in a human bladder carcinoma cell line following Vitamin C and Vitamin K3 treatment

Vitamin K: A novel cancer chemosensitizer

Cancer incidences are growing rapidly and causing millions of deaths globally. Cancer treatment is one of the most exigent challenges. Drug resistance is a natural phenomenon and is considered one of the major obstacles in the successful treatment of cancer by chemotherapy. Combination therapy by the amalgamation of various anticancer drugs has suggested modulating tumor response by targeting various signaling pathways in a synergistic or additive manner. Vitamin K is an essential nutrient and has recently been investigated as a potential anticancer agent. The combination of vitamin K analogs, such as vitamins K1, K2, K3, and K5, with other chemotherapeutic drugs have demonstrated a safe, cost-effective, and most efficient way to overcome drug resistance and improved the outcomes of prevailing chemotherapy. Published reports have shown that vitamin K in combination therapy improved the efficacy of clinical drugs by promoting apoptosis and cell cycle arrest and overcoming drug resistance by inhibiting P-glycoprotein. In this review, we discuss the mechanism, cellular targets, and possible ways to develop vitamin K subtypes into effective cancer chemosensitizers. Finally, this review will provide a scientific basis for exploiting vitamin K as a potential agent to improve the efficacy of chemotherapeutic drugs.

Ascorbate: antioxidant and biochemical activities and their importance for in vitro models

Ascorbate has many biological activities that involve fundamental cellular functions such as gene expression, differentiation, and redox homeostasis. Biochemically, it serves as a cofactor for a large family of dioxygenases (> 60 members) which control transcription, formation of extracellular matrix, and epigenetic processes of histone and DNA demethylation. Ascorbate is also a major antioxidant acting as a very effective scavenger of primary reactive oxygen species. Reduction of Fe(III) by ascorbate is important for cellular uptake of iron via DMT1. Cell culture models are extensively used in toxicology and pharmacology for mechanistic studies of nutrients, drugs and other xenobiotics. High-throughput screens in vitro, such as a large-scale Tox21 program in the US, offers opportunities to assess hazardous properties of a vast and growing number of industrial chemicals. However, cells in typical cultures are severely deficient in ascorbate, raising concerns about their ability to accurately recapitulate toxic and other responses in vivo. Scarcity of ascorbate and a frequently unrecognized use of media with its thiol substitute alters stress sensitivity of cells in different directions. Remediation of ascorbate deficiency in tissue culture restores the physiological state of many cellular processes and it should improve a currently limited toxicity predictability of in vitro bioassays.

High-Dose Vitamin C in Advanced-Stage Cancer Patients

High-dose intravenously administered vitamin C (IVC) is widely used in cancer patients by complementary and alternative medicine practitioners. The most frequent indications for IVC therapy result from the belief in its effectiveness as a potent anti-cancer agent which additionally enhances chemosensitivity of cancer cells and reduces chemotherapy-related toxicities and fatigue intensity. In this narrative review, we decided to deal with this issue, trying to answer the question whether there is any scientific evidence supporting the rationale for application of high-dose IVC therapy in advanced-stage cancer patients. Although results obtained from preclinical studies demonstrated that millimolar ascorbate plasma concentrations achievable only after IVC administration were cytotoxic to fast-growing malignant cells and inhibited tumor growth as well as prolonged the survival of laboratory animals, such positive effects were not found in human studies with advanced-stage cancer patients. We also have not found the rationale for the use of IVC to increase the effectiveness of chemotherapy and to reduce the chemotherapy-induced toxicity in the above mentioned group. Nevertheless, in palliative care, high-dose IVC might be considered as a therapy improving the quality of life and reducing cancer-related symptoms, such as fatigue and bone pain. However, because of the absence of placebo-controlled randomized trials on IVC efficacy in advanced-stage cancer patients, the placebo effect cannot be excluded.

Selective Targeting of Cancerous Mitochondria and Suppression of Tumor Growth Using Redox-Active Treatment Adjuvant

Redox-active substances and their combinations, such as of quinone/ascorbate and in particular menadione/ascorbate (M/A; also named Apatone®), attract attention with their unusual ability to kill cancer cells without affecting the viability of normal cells as well as with the synergistic anticancer effect of both molecules. So far, the primary mechanism of M/A-mediated anticancer effects has not been linked to the mitochondria. The aim of our study was to clarify whether this “combination drug” affects mitochondrial functionality specifically in cancer cells. Studies were conducted on cancer cells (Jurkat, Colon26, and MCF7) and normal cells (normal lymphocytes, FHC, and MCF10A), treated with different concentrations of menadione, ascorbate, and/or their combination (2/200, 3/300, 5/500, 10/1000, and 20/2000 μM/μM of M/A). M/A exhibited highly specific and synergistic suppression on cancer cell growth but without adversely affecting the viability of normal cells at pharmacologically attainable concentrations. In M/A-treated cancer cells, the cytostatic/cytotoxic effect is accompanied by (i) extremely high production of mitochondrial superoxide (up to 15-fold over the control level), (ii) a significant decrease of mitochondrial membrane potential, (iii) a decrease of the steady-state levels of ATP, succinate, NADH, and NAD⁺, and (iv) a decreased expression of programed cell death ligand 1 (PD-L1)—one of the major immune checkpoints. These effects were dose dependent. The inhibition of NQO1 by dicoumarol increased mitochondrial superoxide and sensitized cancer cells to M/A. In normal cells, M/A induced relatively low and dose-independent increase of mitochondrial superoxide and mild oxidative stress, which seems to be well tolerated. These data suggest that all anticancer effects of M/A result from a specific mechanism, tightly connected to the mitochondria of cancer cells. At low/tolerable doses of M/A (1/100-3/300 μM/μM) attainable in cancer by oral and parenteral administration, M/A sensitized cancer cells to conventional anticancer drugs, exhibiting synergistic or additive cytotoxicity accompanied by impressive induction of apoptosis. Combinations of M/A with 13 anticancer drugs were investigated (ABT-737, barasertib, bleomycin, BEZ-235, bortezomib, cisplatin, everolimus, lomustine, lonafarnib, MG-132, MLN-2238, palbociclib, and PI-103). Low/tolerable doses of M/A did not induce irreversible cytotoxicity in cancer cells but did cause irreversible metabolic changes, including: (i) a decrease of succinate and NADH, (ii) depolarization of the mitochondrial membrane, and (iii) overproduction of superoxide in the mitochondria of cancer cells only. In addition, M/A suppressed tumor growth in vivo after oral administration in mice with melanoma and the drug downregulated PD-L1 in melanoma cells. Experimental data suggest a great potential for beneficial anticancer effects of M/A through increasing the sensitivity of cancer cells to conventional anticancer therapy, as well as to the immune system, while sparing normal cells. We hypothesize that M/A-mediated anticancer effects are triggered by redox cycling of both substances, specifically within dysfunctional mitochondria. M/A may also have a beneficial effect on the immune system, making cancer cells “visible” and more vulnerable to the native immune response.

Nuclear and Cytoplasmic Functions of Vitamin C

Vitamin C (ascorbic acid) is a water-soluble antioxidant and a cofactor for a large number of enzymes. It is present in all tissues and especially abundant in corneal epithelium, stem cells, and neurons. Although similar to thiols in its ability to react with many reactive oxygen species (ROS), ascorbate is much better (>100× faster) than glutathione at scavenging of primary ROS (superoxide radical and singlet oxygen). Ascorbate appears to be especially important for elimination of O₂^•– in the nucleus which contains little or no SOD activity. Cofactor functions of ascorbate involve the maintenance of activity of Fe(II)/2-oxoglutarate-dependent dioxygenases via reduction of Fe(III). The most prominent activity of ascorbate-dependent dioxygenases in the cytoplasm is hydroxylation of prolines in proteins involved in the formation of extracellular matrix and regulation of metabolism and hypoxia responses. In the nucleus, ascorbate is important for oxidative demethylation of 5-methylcytosine in DNA (by TET proteins) and removal of methyl groups from histone lysines (by JmjC demethylases). Differentiation and other cellular reprograming processes involving DNA demethylation are especially sensitive to ascorbate insufficiency. High doses of vitamin C alone or in combinations with drugs produced cancer-suppressive effects which involved redox, immune, and epigenetic mechanisms. Solutions to vitamin C deficiency in cultured cells are discussed to improve the physiological relevance of in vitro models. An abundance of vitamin C in rodents limits their ability to fully recapitulate human sensitivity to adverse health effects of malnutrition and xenobiotics, including neurotoxicity, lung injury, and intergenerational and other epigenetic effects.

The combination of ascorbate and menadione causes cancer cell death by oxidative stress and replicative stress

The combination of ascorbate and menadione (VC:VK3 = 100:1) is an investigational treatment for cancer under clinical trials. Dehydroascorbic acid (DHA), the oxidized form of ascorbate, can be taken up by cells via glucose transporters, over-expressed in many cancer cells. It has been known that the combination of VC/VK3 kills cancer cells by inducing hydrogen peroxide (H₂O₂) via a redox cycling reaction. However, the mechanism has not been fully understood yet. Intracellularly, DHA is reduced to ascorbate by NADPH via GSH and glutaredoxin as well as by thioredoxin (Trx) and the selenoenzyme thioredoxin reductase (TrxR). These two systems are also critical as electron donors for ribonucleotide reductase (RNR), which produces deoxyribonucleotides de novo for DNA replication and DNA repair and is highly expressed in tumor cells. We found that RNR was highly sensitive to VC/VK3 in vitro with similar effects as observed with H₂O₂. In cancer cells, VC/VK3 inhibited RNR mainly by targeting its R2 subunit. More importantly, both the Trx and GSH systems were oxidized by the combination, which resulted in the loss of GSH, increased protein glutathionylation, and highly oxidized Trx1. The mechanism of cell death induced by VC/VK3 was also elucidated. We found that VC/VK3 inhibited glutathione peroxidase activity and led to an elevated level of lipid peroxidation, which triggered apoptosis-inducing factor (AIF) mediated cell death pathway. Therefore, the combination not only induced replicative stress by inhibiting RNR, but also oxidative stress by targeting anti-oxidant systems and triggered AIF-mediated cancer cell death.

Selected Office Based Anticancer Treatment Strategies

Over the years, the treatment of patients with cancer has varied widely as much because of recent advancements in science and medicine as the philosophies that belie their use. This paper briefly describes many of the prevailing approaches in use today with an attempt to offer some perspective of how to apply these disparate methodologies so that they may be more effectively integrated, resulting in consistently better clinical responses.

The Combination of Vitamin K3 and Vitamin C Has Synergic Activity against Forms of Trypanosoma cruzi through a Redox Imbalance Process

Chagas' disease is an infection that is caused by the protozoan Trypanosoma cruzi, affecting millions of people worldwide. Because of severe side effects and variable efficacy, the current treatments for Chagas' disease are unsatisfactory, making the search for new chemotherapeutic agents essential. Previous studies have reported various biological activities of naphthoquinones, such as the trypanocidal and antitumor activity of vitamin K3. The combination of this vitamin with vitamin C exerted better effects against various cancer cells than when used alone. These effects have been attributed to an increase in reactive oxygen species generation. In the present study, we evaluated the activity of vitamin K3 and vitamin C, alone and in combination, against T. cruzi. The vitamin K3 + vitamin C combination exerted synergistic effects against three forms of T. cruzi, leading to morphological, ultrastructural, and functional changes by producing reactive species, decreasing reduced thiol groups, altering the cell cycle, causing lipid peroxidation, and forming autophagic vacuoles. Our hypothesis is that the vitamin K3 + vitamin C combination induces oxidative imbalance in T. cruzi, probably started by a redox cycling process that leads to parasite cell death.

Synergistic antitumor cytotoxic actions of ascorbate and menadione on human prostate (DU145) cancer cells in vitro: nucleus and other injuries preceding cell death by autoschizis

Scanning (SEM) and transmission electron microscopy (TEM) were used to characterize the cytotoxic effects of ascorbate (VC), menadione (VK3), or a VC:VK3 combination on a human prostate carcinoma cell line (DU145) following a 1-h vitamin treatment and a subsequent 24-h incubation in culture medium. Cell alterations examined by light and electron microscopy were treatment-dependent with VC + VK3 >VK3 > VC > Sham. Oxidative stress-induced damage was found in most organelles. This report describes injuries in the tumor cell nucleus (chromatin and nucleolus), mitochondria, endomembranes, lysosomal bodies (autophagocytoses) and inclusions. Morphologic alterations suggest that cytoskeleton damage is likely responsible for the superficial cytoplasmic changes, including major changes in cell shape and size and the self-excising phenomena. Unlike apoptotic bodies, the excised pieces contain ribonucleoproteins, but not organelles. These deleterious events cause a progressive, significant reduction in the tumor cell size. During nuclear alterations, the nuclei maintain their envelope during chromatolysis and karyolysis until cell death, while nucleoli undergo a characteristic segregation of their components. In addition, changes in fat and glycogen storage are consistent the cytotoxic and metabolic alterations caused by the respective treatments. All cellular ultrastructural changes are consistent with cell death by autoschizis and not apoptosis or other kinds of cell death.

Ectopic expression of the TERE1 (UBIAD1) protein inhibits growth of renal clear cell carcinoma cells: altered metabolic phenotype associated with reactive oxygen species, nitric oxide and SXR target genes involved in cholesterol and lipid metabolism

Current studies of the TERE1 (UBIAD1) protein emphasize its multifactorial influence on the cell, in part due to its broad sub-cellular distribution to mitochondria, endoplasmic reticulum and golgi. However, the profound effects of TERE1 relate to its prenyltransferase activity for synthesis of the bioactive quinones menaquinone and COQ10. Menaquinone (aka, vitamin K-2) serves multiple roles: as a carrier in mitochondrial electron transport, as a ligand for SXR nuclear hormone receptor activation, as a redox modulator, and as an alkylator of cellular targets. We initially described the TERE1 (UBIAD1) protein as a tumor suppressor based upon reduced expression in urological cancer specimens and the inhibition of growth of tumor cell lines/xenografts upon ectopic expression. To extend this potential tumor suppressor role for the TERE1 protein to renal cell carcinoma (RCC), we applied TERE1 immunohistochemistry to a TMA panel of 28 RCC lesions and determined that in 57% of RCC lesions, TERE1 expression was reduced (36%) or absent (21%). Ectopic TERE1 expression caused an 80% decrease in growth of Caki-1 and Caki-2 cell lines, a significantly decreased colony formation, and increased caspase 3/7 activity in a panel of RCC cell lines. Furthermore, TERE1 expression increased mitochondrial oxygen consumption and hydrogen production, oxidative stress and NO production. Based on the elevated cholesterol and altered metabolic phenotype of RCC, we also examined the effects of TERE1 and the interacting protein TBL2 on cellular cholesterol. Ectopic TERE1 or TBL2 expression in Caki-1, Caki-2 and HEK 293 cells reduced cholesterol by up to 40%. RT-PCR analysis determined that TERE1 activated several SXR targets known to regulate lipid metabolism, consistent with predictions based on its role in menaquinone synthesis. Loss of TERE1 may contribute to the altered lipid metabolic phenotype associated with progression in RCC via an uncoupling of ROS/RNS and SXR signaling from apoptosis by elevation of cholesterol.

Phase I clinical trial to evaluate the safety, tolerability, and pharmacokinetics of high-dose intravenous ascorbic acid in patients with advanced cancer

PURPOSE

This phase I clinical trial evaluated the safety, tolerability, and pharmacokinetics of high-dose intravenous (i.v.) ascorbic acid as a monotherapy in patients with advanced solid tumors refractory to standard therapy.

METHODS

Five cohorts of three patients received i.v. ascorbic acid administered at 1 g/min for 4 consecutive days/week for 4 weeks, starting at 30 g/m² in the first cohort. For subsequent cohorts, dose was increased by 20 g/m² until a maximum tolerated dose was found.

RESULTS

Ascorbic acid was eliminated by simple first-order kinetics. Half-life and clearance values were similar for all patients of all cohorts (2.0 ± 0.6 h, 21 ± 5 dL/h m², respectively). C(max) and AUC values increased proportionately with dose between 0 and 70 g/m², but appeared to reach maximal values at 70 g/m² (49 mM and 220 h mM, respectively). Doses of 70, 90, and 110 g/m² maintained levels at or above 10-20 mM for 5-6 h. All doses were well tolerated. No patient demonstrated an objective antitumor response.

CONCLUSIONS

Ascorbic acid administered i.v. at 1 g/min for 4 consecutive days/week for 4 weeks produced up to 49 mM ascorbic acid in patient's blood and was well tolerated. The recommended dose for future studies is 70-80 g/m².

Ascorbic acid: chemistry, biology and the treatment of cancer

Since the discovery of vitamin C, the number of its known biological functions is continually expanding. Both the names ascorbic acid and vitamin C reflect its antiscorbutic properties due to its role in the synthesis of collagen in connective tissues. Ascorbate acts as an electron-donor keeping iron in the ferrous state thereby maintaining the full activity of collagen hydroxylases; parallel reactions with a variety of dioxygenases affect the expression of a wide array of genes, for example via the HIF system, as well as via the epigenetic landscape of cells and tissues. In fact, all known physiological and biochemical functions of ascorbate are due to its action as an electron donor. The ability to donate one or two electrons makes AscH(-) an excellent reducing agent and antioxidant. Ascorbate readily undergoes pH-dependent autoxidation producing hydrogen peroxide (H(2)O(2)). In the presence of catalytic metals this oxidation is accelerated. In this review, we show that the chemical and biochemical nature of ascorbate contribute to its antioxidant as well as its prooxidant properties. Recent pharmacokinetic data indicate that intravenous (i.v.) administration of ascorbate bypasses the tight control of the gut producing highly elevated plasma levels; ascorbate at very high levels can act as prodrug to deliver a significant flux of H(2)O(2) to tumors. This new knowledge has rekindled interest and spurred new research into the clinical potential of pharmacological ascorbate. Knowledge and understanding of the mechanisms of action of pharmacological ascorbate bring a rationale to its use to treat disease especially the use of i.v. delivery of pharmacological ascorbate as an adjuvant in the treatment of cancer.

2-Bromo-1,4-naphthoquinone: a potentially improved substitute of menadione in Apatone™ therapy

Apatone™, a combination of menadione (2-methyl-1,4-naphthoquinone, VK3) and ascorbic acid (vitamin C, VC) is a new strategy for cancer treatment. Part of its effect on tumor cells is related to the cellular pro-oxidative imbalance provoked by the generation of hydrogen peroxide (H2O2) through naphthoquinone redox cycling. In this study, we attempted to find new naphthoquinone derivatives that would increase the efficiency of H2O2 production, thereby potentially increasing its efficacy for cancer treatment. The presence of an electron-withdrawing group in the naphthoquinone moiety had a direct effect on the efficiency of H2O2 production. The compound 2-bromo-1,4-naphthoquinone (BrQ), in which the bromine atom substituted the methyl group in VK3, was approximately 10- and 19-fold more efficient than VK3 in terms of oxygen consumption and H2O2 production, respectively. The ratio [H2O2]produced / [naphthoquinone]consumed was 68 ± 11 and 5.8 ± 0.2 (µM/µM) for BrQ and VK3, respectively, indicating a higher efficacy of BrQ as a catalyst for the autoxidation of ascorbic acid. Both VK3 and BrQ reacted with glutathione (GSH), but BrQ was the more effective substrate. Part of GSH was incorporated into the naphthoquinone, producing a nucleophilic substitution product (Q-SG). The depletion of BrQ by GSH did not prevent its redox capacity since Q-SG was also able to catalyze the production of reactive oxygen species. VK3/VC has already been submitted to clinical trials for the treatment of prostate cancer and has demonstrated promising results. However, replacement of VK3 with BrQ will open new lines of investigation regarding this approach to cancer treatment.

The bladder tumor suppressor protein TERE1 (UBIAD1) modulates cell cholesterol: implications for tumor progression

Convergent evidence implicates the TERE1 protein in human bladder tumor progression and lipid metabolism. Previously, reduced TERE1 expression was found in invasive urologic cancers and inhibited cell growth upon re-expression. A role in lipid metabolism was suggested by TERE1 binding to APOE, a cholesterol carrier, and to TBL2, a candidate protein in triglyceride disorders. Natural TERE1 mutations associate with Schnyder's corneal dystrophy, characterized by lipid accumulation. TERE1 catalyzes menaquinone synthesis, known to affect cholesterol homeostasis. To explore this relationship, we altered TERE1 and TBL2 dosage via ectopic expression and interfering RNA and measured cholesterol by Amplex red. Protein interactions of wild-type and mutant TERE1 with GST-APOE were evaluated by binding assays and molecular modeling. We conducted a bladder tumor microarray TERE1 expression analysis and assayed tumorigenicity of J82 cells ectopically expressing TERE1. TERE1 expression was reduced in a third of invasive specimens. Ectopic TERE1 expression in J82 bladder cancer cells dramatically inhibited nude mouse tumorigenesis. TERE1 and TBL2 proteins inversely modulated cellular cholesterol in HEK293 and bladder cancer cells from 20% to 50%. TERE1 point mutations affected APOE interactions, and resulted in cholesterol levels that differed from wild type. Elevated tumor cell cholesterol is known to affect apoptosis and growth signaling; thus, loss of TERE1 in invasive bladder cancer may represent a defect in menaquinone-mediated cholesterol homeostasis that contributes to progression.

The bladder tumor suppressor protein TERE1 (UBIAD1) modulates cell cholesterol: implications for tumor progression

Convergent evidence implicates the TERE1 protein in human bladder tumor progression and lipid metabolism. Previously, reduced TERE1 expression was found in invasive urologic cancers and inhibited cell growth upon re-expression. A role in lipid metabolism was suggested by TERE1 binding to APOE, a cholesterol carrier, and to TBL2, a candidate protein in triglyceride disorders. Natural TERE1 mutations associate with Schnyder's corneal dystrophy, characterized by lipid accumulation. TERE1 catalyzes menaquinone synthesis, known to affect cholesterol homeostasis. To explore this relationship, we altered TERE1 and TBL2 dosage via ectopic expression and interfering RNA and measured cholesterol by Amplex red. Protein interactions of wild-type and mutant TERE1 with GST-APOE were evaluated by binding assays and molecular modeling. We conducted a bladder tumor microarray TERE1 expression analysis and assayed tumorigenicity of J82 cells ectopically expressing TERE1. TERE1 expression was reduced in a third of invasive specimens. Ectopic TERE1 expression in J82 bladder cancer cells dramatically inhibited nude mouse tumorigenesis. TERE1 and TBL2 proteins inversely modulated cellular cholesterol in HEK293 and bladder cancer cells from 20% to 50%. TERE1 point mutations affected APOE interactions, and resulted in cholesterol levels that differed from wild type. Elevated tumor cell cholesterol is known to affect apoptosis and growth signaling; thus, loss of TERE1 in invasive bladder cancer may represent a defect in menaquinone-mediated cholesterol homeostasis that contributes to progression.

The bladder tumor suppressor protein TERE1 (UBIAD1) modulates cell cholesterol: implications for tumor progression

Convergent evidence implicates the TERE1 protein in human bladder tumor progression and lipid metabolism. Previously, reduced TERE1 expression was found in invasive urologic cancers and inhibited cell growth upon re-expression. A role in lipid metabolism was suggested by TERE1 binding to APOE, a cholesterol carrier, and to TBL2, a candidate protein in triglyceride disorders. Natural TERE1 mutations associate with Schnyder's corneal dystrophy, characterized by lipid accumulation. TERE1 catalyzes menaquinone synthesis, known to affect cholesterol homeostasis. To explore this relationship, we altered TERE1 and TBL2 dosage via ectopic expression and interfering RNA and measured cholesterol by Amplex red. Protein interactions of wild-type and mutant TERE1 with GST-APOE were evaluated by binding assays and molecular modeling. We conducted a bladder tumor microarray TERE1 expression analysis and assayed tumorigenicity of J82 cells ectopically expressing TERE1. TERE1 expression was reduced in a third of invasive specimens. Ectopic TERE1 expression in J82 bladder cancer cells dramatically inhibited nude mouse tumorigenesis. TERE1 and TBL2 proteins inversely modulated cellular cholesterol in HEK293 and bladder cancer cells from 20% to 50%. TERE1 point mutations affected APOE interactions, and resulted in cholesterol levels that differed from wild type. Elevated tumor cell cholesterol is known to affect apoptosis and growth signaling; thus, loss of TERE1 in invasive bladder cancer may represent a defect in menaquinone-mediated cholesterol homeostasis that contributes to progression.

Cell damage and death by autoschizis in human bladder (RT4) carcinoma cells resulting from treatment with ascorbate and menadione

A human bladder carcinoma cell line RT4 was sham-treated with buffer or treated with ascorbate (VC) alone, menadione alone (VK(3)), or a combination of ascorbate:menadione (VC+VK(3)) for 1, 2, and 4 h. Cytotoxic damage was found to be treatment-dependent in this sequence: VC+VK(3)>VC>VK(3)>sham. The combined treatment induced the greatest oxidative stress, with early tumor cell injury affecting the cytoskeletal architecture and contributing to the self-excisions of pieces of cytoplasm freed from organelles. Additional damage, including a reduction in cell size, organelle alterations, nuclear damage, and nucleic acid degradation as well as compromised lysosome integrity, is caused by reactivation of DNases and the redox cycling of VC or VC+VK(3). In addition, cell death caused by VC+VK(3) treatment as well as by prolonged VC treatment is consistent with cell demise by autoschizis, not apoptosis. This report confirms and complements previous observations about this new mode of tumor cell death. It supports the contention that a combination of VC+VK(3), also named Apatone, could be co-administered as a nontoxic adjuvant with radiation and/or chemotherapies to kill bladder tumor cells and other cancer cells without any supplementary risk or side effects for patients.

Pankiller effect of prolonged exposure to menadione on glioma cells: potentiation by vitamin C

Menadione (Vitamin K3) has anti-tumoral effects against a wide range of cancer cells. Its potential toxicity to normal cells and narrow therapeutic range limit its use as single agent but in combination with radiation or other anti-neoplastic agents can be of therapeutic use. In this paper, we first evaluated the early (within 3 h) effect of menadione on ongoing DNA replication. In normal rat cerebral cortex mini-units menadione showed an age dependent anti-proliferative effect. In tissue mini-units prepared from newborn rats, menadione inhibited ongoing DNA replication with an IC ₅₀ of approximately 10 μM but 50 μM had no effect on mini-units from prepared adult rat tissue. The effect of short (72 h) and prolonged exposure (1–2 weeks) to menadione alone in the DBTRG.05MG human glioma cells line and in combination with vitamin C was studied. After short period of exposure data show that menadione alone or in combination with vitamin C provided similar concentration-response curves (and IC₅₀ values). Prolonged exposure to these drugs was evaluated by their ability to kill 100% of glioma cells and prevent regrowth when cells are re-incubated in drug-free media. In this long-term assay, menadione:vitamin C at a ratio 1:100 showed higher anti-proliferative activity when compared to each drug alone and allowed to reduce each drug concentration between 2.5 to 5-fold. Similar anti-proliferative effect was demonstrated in 8 patient derived glioblastoma cell cultures. Our data should be able to encourage further advanced studies on animal models to evaluate the potential use of this combination therapy for glioma treatment.

Nucleolar changes and fibrillarin redistribution following apatone treatment of human bladder carcinoma cells

Ascorbate and menadione (Apatone) in a ratio of 100:1 kills tumor cells by autoschizis. In this study, vitamin-induced changes in nucleolar structure were evaluated as markers of autoschizis. Human bladder carcinoma (T24) cells were overlain with vitamins or with culture medium. Supernatants were removed at 1-hr intervals from 1 to 4 hr, and the cells were washed with PBS and prepared for assay. Apatone produced marked alterations in nucleolar structure including redistribution of nucleolar components, formation of ring-shaped nucleoli, condensation and increase of the proportion of perinucleolar chromatin, and the enlargement of nucleolar fibrillar centers. Immunogold labeling of the nucleolar rRNA revealed a granular localization in treated and sham-treated cells, and immunogold labeling of the rDNA revealed a shift from the fibrillar centers to the condensed perinucleolar chromatin. Fibrillarin staining shifted from the fibrillar centers and adjacent regions to a more homogeneous staining of the entire nucleolus and was consistent with the percentage of autoschizic cells detected by flow cytometry. Because autoschizis entails sequential reactivation of DNase I and DNase II, and because the fibrillarin redistribution following DNase I and Apatone treatment is identical, it appears that the nucleolar and fibrillarin changes are markers of autoschizis.

Synthesis and antitumor evaluation of 8-phenylaminopyrimido[4,5-c]isoquinolinequinones

A series of 8-phenylaminopyrimido[4,5-c]isoquinoline-7,10-quinone derivatives were prepared by regioselective amination reaction of pyrimido[4,5-c]isoquinoline-7,10-quinones with arylamines in the presence of a Lewis acid catalyst. Preliminary evaluation of the members of the series against cancer cell lines and assays of activation of their cytotoxic activity on K562 cells with ascorbic acid are reported.

Cell Death by Autoschizis in TRAMP Prostate Carcinoma Cells as a Result of Treatment by Ascorbate: Menadione Combination

A prostate carcinoma cell line derived from the transgenic murine prostate cancer model (TRAMP) was treated with ascorbate (VC) alone, menadione (VK(3)) alone, or a combination of ascorbate:menadione (VC + VK(3)) for 1, 2, and 4 h. Cytotoxic cell alterations examined by light and electron microscopy were treatment-dependent with VC + VK(3) > VC > VK(3). Induced by oxidative stress, these alterations included cytokeletal changes conducive to cytoplasmic blebbing, self-excisions, and progressive nuclear alterations. While the excised parts contained ribosomes, they were devoid of nuclear fragments or other organelles. The organelle-free self-excisions caused an extreme reduction in cell size as well as chromatolysis and karyolysis that were consistent with cell death by autoschizis, but not with apoptosis.

Hsp90 cleavage by an oxidative stress leads to its client proteins degradation and cancer cell death

The heat shock protein 90 (Hsp90) plays a crucial role in the stability of several proteins that are essential for malignant transformation. Hsp90 is therefore an interesting therapeutic target for cancer therapy. In this paper, we investigated whether an oxidative stress generated during ascorbate-driven menadione redox cycling (ascorbate/menadione), affects Hsp90 leading to the degradation of some critical proteins and cell death. Unlike 17-AAG, which inhibits Hsp90 but enhances Hsp70 levels, ascorbate/menadione-treated cells present an additional Hsp90 protein band of about 70kDa as shown by Western blot analysis, suggesting Hsp90 cleavage. This Hsp90 cleavage seems to be a selective phenomenon since it was observed in a large panel of cancer cell lines but not in non-transformed cells. Antibodies raised against either the N-terminus or the C-terminus domains of Hsp90 suggest that the site of cleavage should be located at its N-terminal part. Furthermore, antibodies raised against either the alpha- or the beta-Hsp90 isoform show that Hsp90beta is cleaved while the alpha isoform is down-regulated. We have further shown that different Hsp90 client proteins like Bcr-Abl (a chimerical protein expressed in K562 leukemia cells), RIP and Akt, were degraded when K562 cells were exposed to an oxidative stress. Both Hsp90 cleavage and Bcr-Abl degradation were observed by incubating K562 cells with another H(2)O(2)-generating system (glucose/glucose oxidase) and by incubating KU812 cells (another leukemia cell line) with ascorbate/menadione. Due to the major role of Hsp90 in stabilizing oncogenic and mutated proteins, these results may have potential clinical applications.

The molecular mechanisms of vitamin C on cell cycle regulation in B16F10 murine melanoma

Vitamin C has inconsistent effects on malignant tumor cells, which vary from growth stimulation to apoptosis induction. It is well known that melanoma cells are more susceptible to vitamin C than any other tumor cells, but the precise mechanism remains to be elucidated. In the present study, the proliferation of B16F10 melanoma cells was suppressed by vitamin C, which induced growth arrest in a dose-dependent manner without cytotoxic effects. Therefore, we investigated the changes in cell cycle distribution of B16F10 melanoma cells by staining DNAs with propidium iodide (PI). The growth inhibition of B16F10 melanoma by vitamin C was associated with an arrest of cell cycle distribution at G1 stage. In addition, the levels of p53-p21Waf1/Cip1 increased during G1 arrest, which were essential for vitamin C-induced cell cycle arrest. The increased p21Waf1/Cip1 inhibited CDK2. Moreover, the activity of p53-p21Waf1/Cip1 pathway was closely related with the activation of checkpoint kinase 2 (Chk2). Inhibitor of the PI3K-family, LY294002 and the ATM/ATR inhibitor, caffeine, blocked vitamin C-induced growth arrest in B16F10 melanoma cells. These results suggest that vitamin C might be a potent agent to inhibit proliferative activity of melanoma cells via the regulation of Chk2-p53-p21Waf1/Cip1 pathway.

Vitamin B12b increases the cytotoxicity of short-time exposure to ascorbic acid, inducing oxidative burst and iron-dependent DNA damage

It has been found previously that hydroxycobalamine (vitamin B12b) amplifies significantly the cytotoxic effect of ascorbic acid (vitamin C) added to cells for small a, Cyrillic long period of time (48 h). However, according to pharmacokinetics, the concentration of vitamin C in vivo decreases to a physiological value within a short period of time (2-3 h) after the injection. Therefore, in this study we examined the cytotoxic effect of a short-time (up to 2 h) exposure of human larynx carcinoma HEp-2 cells to a combination of vitamins B12b and C (B12b+C). The kinetics of the B12b+C-caused extracellular oxidative burst in this time interval was also explored. Vitamin B12b combined with ascorbic acid provoked a rapid accumulation of extracellular hydrogen peroxide followed by intracellular oxidative stress, DNA single-strand breaks, and the initiation of apoptosis. The chelators of iron phenanthroline and desferrioxamine prevented B12b+C-induced DNA single-strand breaks and cell death but not the accumulation of H2O2 in culture medium. The nonthiol antioxidants pyruvate and catalase were effective in preventing the prooxidant and cytotoxic effects of B12b+C. Thiols, when added simultaneously with the combined vitamins, inhibited these effects only partially (N-acetylcysteine, GSH) or even amplified them (dithiothreitol). The results obtained point to the determining role of oxidative burst and iron-dependent DNA damage in the cytotoxic effect of short-time exposure to B12b+C combination.

Human urinary bladder cancer T24 cells are susceptible to the Antrodia camphorata extracts

Bladder cancer has been cited to result from the neoplastic lesion with environmental and/or occupational factors identified as causatives. Transitional cell carcinoma (TCC) is the most common type of bladder cancer. Most of the bladder cancer patients die from the invasive, metastatic TCC that has turned out to be resistant to chemotherapy. T24 cells, a cell line established from a human urinary bladder cancer patient, are high-grade and invasive TCC. T24 cells were found very susceptible to ACCE at concentration of 50 microg/mL. MTT assay showed that the cell growth and proliferation were inhibited to 50% of the control when treated with ACCE for 72 h, at which the cell proliferation suppressing rate revealed -4.4 x 10(3)cells/microg per day. Comparing the expressions of the cell cycle biomarkers Cdc2 and Cyclin B1 by the western blot analysis, a phase G(2)M arrest was confirmed. Both the wound scratch assay and the transwell motility assay indicated that ACCE was very effective anti-metastatic against T24 cells. Furthermore, the active form of matrix metalloproteinase-9 (MMP-9) was also found totally suppressed as revealed by zymography at 72 h post-incubation with ACCE, while the light and electron microscopic images have apparently revealed cell membrane damages on T24 cells when treated with ACCE (50 microg/mL). Moreover, both the wound scratch and the transwell assays have demonstrated the migration capability of T24 cells has been significantly retarded to 1.5-fold at same dosage of ACCE used. In conclusion, ACCE is a good anti-cancer agent, being effective in inducing phase G(2)M arrest, acting as an anti-proliferative, and an anti-metastatic agent against bladder cancer cell T24 cells.

Enhancement of quinone redox cycling by ascorbate induces a caspase-3 independent cell death in human leukaemia cells. An in vitro comparative study

Since the higher redox potential of quinone molecules has been correlated with enhanced cellular deleterious effects, we studied the ability of the association of ascorbate with several quinones derivatives (having different redox potentials) to cause cell death in K562 human leukaemia cell line. The rationale is that the reduction of quinone by ascorbate should be dependent of the quinone half-redox potential thus determining if reactive oxygen species (ROS) are formed or not, leading ultimately to cell death or cell survival. Among different ROS that may be formed during redox cycling between ascorbate and the quinone, the use of different antioxidant compounds (mannitol, desferal, N-acetylcysteine, catalase and superoxide dismutase) led to support H2O2 as the main oxidizing agent. We observed that standard redox potentials, oxygen uptake, free ascorbyl radical formation and cell survival were linked. The oxidative stress induced by the mixture of ascorbate and the different quinones decreases cellular contents of ATP and GSH while caspase-3-like activity remains unchanged. Again, we observed that quinones having higher values of half-redox potential provoke a severe depletion of ATP and GSH when they were associated with ascorbate. Such a drop in ATP content may explain the lack of activation of caspase-3. In conclusion, our results indicate that the cytotoxicity of the association quinone/ascorbate on K562 cancer cells may be predicted on the basis of half-redox potentials of quinones.

Apoptosis induction by Epican Forte in HTLV-1 positive and negative malignant T-cells

The effects of a novel nutrient formulation Epican Forte (EF) were evaluated on proliferation and induction of apoptosis using non-cytotoxic concentrations against HTLV-1 positive (HuT-102 & C91-PL) and negative (CEM & Jurkat) cells. EF showed anti-proliferative effect as determined by MTT assay and TGF mRNA protein expression using RT-PCR. EF resulted in the down-regulation of TGF-alpha and an up-regulation in TGF-beta2. EF caused a significant increase in apoptotic cells in the preG1 phase. These results were confirmed using Cell Death ELISA and Annexin V-FITC. Induction of apoptosis was caused by an up-regulation of p53, p21 and Bax protein levels and a down-regulation of Bcl-2alpha protein expression level.

Morphology and DNA degeneration during autoschizic cell death in bladder carcinoma T24 cells induced by ascorbate and menadione treatment

Feulgen and actin-phalloidin staining as well as gel electrophoresis have been employed in conjunction with cell ultrastructure to describe the effects of 1-, 2-, and 4-hr ascorbate (VC), menadione (VK(3)), and ascorbate:menadione (VC:VK(3)) treatments on the T24 human bladder carcinoma cell line. T24 cells exposed to VC alone display blebs and other superficial membrane defects related to membrane alterations and to superficial cytoskeleton changes. VK(3) treatment damages the cell nucleus and organelles, leads to the redistribution of the organelles in the perikaryon as a consequence of cytoskeletal damage, and results in cytoplasmic self-excisions. After VC:VK(3) treatment, the cells show exaggerated alterations characteristic of each vitamin treatment alone, including damaged mitochondria, self-excision of organelle-free pieces of cytoplasm, and extrusion of the perikaryon containing a nucleus surrounded by the damaged organelles. The nuclear envelope appears intact and contains chromatin that decondenses and dissipates. During the cellular demise that concludes with apparent karyolysis, the cells significantly decrease their size and alter their shape. However, the cisterns of rough endoplasmic reticulum are undamaged, but may become dilated. Since the cellular phenomena leading to cell death differ morphologically from apoptosis and necrosis, but entail self-cutting without nuclear bodies, this new form of cell death was called autoschizis. In addition, gel electrophoresis and Feulgen staining demonstrate that autoschizis is accompanied by random DNA degeneration.

Autoschizis: a new form of cell death for human ovarian carcinoma cells following ascorbate:menadione treatment. Nuclear and DNA degradation

Microscopic aspects, densitometric evaluation of Feulgen-stained DNA, and gel electrophoresis of total DNA have been used to elucidate the effects of 1, 2, and 3 h VC (ascorbic acid), VK3 (menadione), and combined VC:VK3 treatments on the cellular and nuclear morphology and DNA content of a human ovarian carcinoma cell line (MDAH 2774). Optical densitometry showed a significant decrease in cancer cell DNA content directly related to VC and VC:VK3 treatments while VK3 and VC:VK3 treated cells exhibited cytoskeletal changes that included self-excision of cytoplasmic pieces with no membranous organelles. Nuclei decreased in size and exhibited poor contrast consistent with progressive decondensation of their chromatin. Degraded chromatin was also detected in cytoplasmic autophagosomes. Nucleoli segregated their components and fragmented into small pieces. Gel electrophoretic analysis of total DNA revealed evidence of generalized DNA degradation specific to treated tumor cells. These results are consistent with previous observations [Scanning 20 (1998a) 564; Ultrastruct. Pathol. 25 (2001b) 183; J. Histochem. Cytochem. 49 (2001) 109] which demonstrated that the VC:VK3 combination induced autoschizic cell death by a series of cytoplasmic excisions without organelles along with specific nuclear ultrastructural damage.